I. Field of the Invention
This invention relates to a system for removing contaminants from a water supply and, in particular, to a nozzle/venturi assembly for use in such a system to precisely control and maintain the amount of air which is entrained into the fluid stream during the complete cycle of the water system.
II. Description of the Prior Art
Systems for removing impurities such as iron, sulphur and man-made contaminants from a water supply have been developed and refined over the years in order to provide a safe and palatable water supply. Generally, these systems include chlorination and filtration of the water to remove the contaminants. However, many contaminants must first be oxidized to permit removal through filtration. As a result, several of the past known systems employ means for entraining air into the water stream to facilitate removal of the contaminants.
Several of the past known filtering systems utilize venturi assemblies to entrain the air into the fluid stream. The simple nozzle/venturi works well where the pressure differential is stable and a constant fluid flow through the nozzle is maintained. However, any variations and the amount of entrained air may not be enough for removal of the contaminants or may be too much for efficient operation of the system. As a result, bypass means were added to the nozzle/venturi to more accurately control the water/air mixture. The bypass may form a segregated portion of the nozzle with the nozzle/venturi mounted parallel thereto. However, such systems do not provide efficient diversion since both the bypass and the nozzle/venturi are disposed within the same chamber. The bypass has also been restricted by a diaphragm to continuously vary the fluid flow through the bypass. However, such systems are dependent upon the elastic properties of the diaphragm and true control of the entrainment process is not provided. The amount of flow through the bypass necessary to open the diaphragm will always be the same and cannot be varied from system to system or as the differential pressure varies. Thus, simple and accurate means of controlling the differential pressure necessary to open the bypass passageway are needed to provide efficient removal of contaminants from a water supply.